US3513094A - Lubricant compositions - Google Patents

Description

United States Patent M LUBRICANT COMPOSITIONS Homer H. Farmer, Westport, Harold F. Tompkins, Trumbull, and Bobby W. Malone, Norwalk, 'Conm, assignors to R. T. Vanderbilt Company, Inc., New

York, N.Y., a corporation of New York No Drawing. Filed Apr. 26, 1967, Ser. No. 633,677

Int. Cl. Cltlm N48 US. Cl. 25232.7 8 Claims ABSTRACT OF THE DISCLOSURE An improved extreme pressure lubricant combining an antimony dihydrocarbylphosphorodithioate with a second, known extreme pressure or wear inhibiting agent, such as chlorinated paraffin, sulfurized oil, a lead dithiocarbamate or lead naphthenate, in a lubricating oil or lubricating grease base.

This invention relates to improved lubricant composi tions, and more particularly to lubricant compositions containing antimony dihydrocarbylphosphorodithioates combined with other wear inhibitors and extreme pressure agents in a lubricating oil base.

There are several types of gears and bearings, such as hypoid gears and heavily loaded bearings, wherein it is extremely difiicult to maintain a thin film of lubricant between the gear or bearing surfaces. When the film of lubricant ruptures, the high spots on the surfaces where metal-to-metal contact occurs become deformed. The friction increases to cause localized welding. As the weld is sheared by the relative motion of the surfaces, particles of metal are removed. The contacting surfaces become rough and pitted, and they eventually fail by seizing or scoring.

The special types of lubricants developed for use under these conditions are known as extreme pressure (E.P.) lubricants. E.P. lubricants are prepared by adding special E.P. agents to lubricating oils or greases. Other antiwear and anticorrosion agents are often added to prepare a lubricant with several desirable special properties.

It has been proposed heretofore to add various metallic salts of dihydrocarbyl esters of phosphorodithioic acids as E.P. agents and wear inhibitors to lubricating oils or greases in order to prepare E.P. and antiwear lubricating compositions. Many of these proposed E.P. lubricants have exhibited only moderately acceptable BF. and antiwear properties.

It is therefore an object of the present invention to provide improved lubricating compositions exhibiting highly effective extreme pressure and antiwear properties.

According to the invention it has been found that antimony dihydrocarbylphosphorodithioates combined with other well-known ER and antiwear agents in lubricating oils and greases exhibit surprising and unexpected synergistic RP. and antiwear properties. The lubricating compositions of the invention are suitable for use on heavily loaded surfaces where extreme pressure conditions prevail to prevent scufling and seizure of engaging movable parts. Examples of the suitable uses include gear oils, crankcase oils, cutting oils, metal working lubricants, hydraulic fluids and automatic transmission fluids.

The antimony dihydrocarbylphosphorodithioates used in the invention have the structural formula:

3,513,094 Patented May 19, 1970 wherein R is a hydrocarbyl radical selected from the group consisting of (A) lower alkyl radicals containing from two to eight carbon atoms, such as ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec.-butyl, tert.-butyl, amyl, nhexyl, ihexyl, n-heptyl, n-octyl, i-octyl, and 2-ethylhexyl; (B) substituted and unsubstituted cycloalkyl radicals containing five or six carbon atom rings, with the substituted cycloalkyls containing at least one of the lower alkyl radicals, e.g., cyclopentyl, methylcyelopentyl, cyclohexyl, methyl cyclohexyl and ethylcyclohexyl; and (C) substituted and unsubstituted phenyl radicals with the substituted phenyl radicals containing at least one of the substituents selected from the group consisting of alkyl radicals containing from one to nine carbon atoms. Examples of the substituted phenyl radicals include cresyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, amylphenyl, octylphenyl and nonylphenyl groups.

The other BF. and antiwear additives operable in the invention include the well-known E.P. agents, exemplified by lead naphthenate, halogenated paraffin, sulfurized fatty oils, and metal dialkyldithiocarbamates, wherein the metals include molybdenum, antimony, cadmium, zinc and lead, and the alkyl groups range from C to C The ratios of the amounts of antimony dihydrocarbylphosphorodithioates to other E.P. additives vary with the type of supplemental E.P. additive employed, as well as with the length of the hydrocarbyl group in the antimony dihydrocarbylphosphorodithioates. It has been found, however, that as low as 0.2% antimony dihydrocarbylphosphorodithioate and 0.4% supplemental E.P. additives will provide significant synergistic levels of BF. performance.

The lubricating oil base stock used in preparing the lubricating composition may be straight mineral lubricating oils, distillates, greases, bright stock residua, etc. Synthetic lubricating oils, such as hydrogenated oils, glycol ethers, dibasic acid esters, and other polyester and polyether synthetic lubricating oils can also be used, as can mixtures of the synthetic oils. It is also possible to employ mixtures of synthetic oils and petroleum base mineral oils as the base.

The lubricating compositions may contain other components if desired, such as dispersing agents, rust inhibitors, antioxidants, and pour depressants.

In the following examples, the antimony dihydrocarbylphosphorodithioates were prepared by conventional means. The examples are intended to illustrate the prop erties of the lubricating compositions, including both oils and greases, as described in this specification, and are not intended to limit in any way the scope of the invention.

EXAMPLE 1 Timken Load-Bearing Test using antimony di-n-propylphosphorodithioate and chlorinated paraffin To separate portions of a representative solvent-refined, hydro-treated, high viscosity index, SAE Mid-Continent base oil were added: 0.25% by weight of chlorinated parafiin (described as containing 42.45% combined chlorine and having a specific gravity of 1.1654210 and an SUS viscosity at 210 F. of 184-192 seconds); 1.0% chlorinated paraffin; 0.75% antimony di-n-propylphosphorodithioate; 1% antimony di-n-propylphosphorodithioate; a combination of 0.25% chlorinated paraffin and 0.75% of the antimony phosphorodithioate; and a combination of 0.1% chlorinated paraflin and 0.3% of the antimony phosphorodithioate. An untreated portion of the base oil served as a control.

The lubricating compositions so produced were subjected to the Timken Load-Bearing Test in the Timken Lubricant Tester in which a hardened steel ring rotating at 800 r.p.m. was flooded by the test lubricant at F.

while a hardened steel block was pressed against it by a system of weights and levers. The highest weight which did not produce scoring of the block in minutes running time was recorded as the passing load or O.K. load, which is a recognized measure of the load-carrying capacity of the lubricant. The values obtained in accordance with this standard test are set forth in Table I below.

These data show that the observed load increase for the combination of 0.25% chlorinated paraflin and 0.75% antimony phosphorodithioate was 68 lbs.; whereas the calculated increase is 31 lbs., which is less than onehalf the observed increase. The observed load increase for 0.1% chlorinated parafiin and 0.3% antimony phosphorodithioate was 18 lbs., and the calculated increase is 12 lbs. which is two-thirds the observed increase.

EXAMPLE 2 Timken Load-Bearing Test using, antimony bis(2-ethylhexyl)phosphorodithioate and chlorinated paralfin To separate portions of the base oil described in Example 1 were added 0.4% by weight of chlorinated paraffin, 2% by weight of antimony bis(2-ethylhexyl) phosphorodithioate, and a combination of 0.4% of chlorinated parafiin and 2% of antimony bis(2-ethylhexyl) phosphorodithioate. An untreated portion of the base oil served as a control. The lubricating compositions so produced were subjected to the Timken Load-Bearing Test with the following results:

These data show that the actual increase in load-bearing capacity of the oil containing the combination of chlorinated parafiin and the antimony phosphorodithioate (58 lb. over that of the base oil) is far in excess of that which could be expected from additive effect alone (39 lbs. over base oil).

EXAMPLE 3 Timken Load-Bearing Test using antimony di-n-propylphosphorodithioate and lead naphthenate To separate portions of the base oil described in Example 1 were added 1.5% by weight of light colored lead naphthenate (containing 30% lead), 0.75 antimony di-n-propylphosphorodithioate, a combination of 1.5% lead naphthenate and 0.75 antimony di-n-propylphosphorodithioate, and a combination of 0.4% lead napthenate and 0.2% of the antimony phosphorodithioate. An untreated portion of the base oil served as the control. The lubricating compositions thus formed were subjected to the Timken Load-Bearing Test with the results tabulated below.

TABLE III SAE base oil containing Sb di-npropylphosphorodithioate,

percent Lead naphthenate, percent Observed Thus it is shown that the OK. load of oil containing both of the additives is increased twice as much (73 lbs.) as could be expected on the basis of additives eflFect alone (36 lbs.).

EXAMPLE 4 4-Ball Weld Load Test using antimony bis(2-ethylhexyl)- phosphorodithioate and lead naphthenate To separate portions of the oil described in Example 1 were added: 1.5% by weight of lead naphthenate; 3.0% by weight of antimony bis(2-ethylhexyl)phosphorodithioate; a combination of 1.5% lead naphthenate and 3.0% antimony bis(Z-ethylhexyl)phosphorodithioate; and a combination of 0.5% lead naphthenate and 1.0% antimony bis(2-ethylhexyl)phosphorodithioate. An untreated portion of the oil served as a control. The compositions thus prepared were subjected to the 4-Ball Weld Load Test in which a /2-inch steel ball is rotated in contact with three similar balls which are clamped in a stationary position so as to provide three points of contact. The balls are bathed in lubricating composition at room temperature, and increasing loads are applied for ten seconds each to the ball rotating at 1800 r.p.m. The load at which the balls weld together is recorded. The results of these tests are reported below.

TABLE IV SAE 90 base oil containing Sb bis(2- 4-ball weld load, Kg. ethylhexyD- Lead phosphoro- Increase naphthenate, dithioate, percent percent Observed Observed Calculated These data show that there is a far greater than additive effect on the 4-Ball Weld Load when 1.5% lead naphthenate and 3.0% antimony bis(2-ethylhexyl)-phosphorodithioate are used together than when used alone. The expected increase was 35 kg. due to lead naphthenate and kg. due to the phosphorodithioate, a total of kg. while the actual increase was 225 kg.

When the quantities of each of these additives were cut to one-third, the expected increase would be one-third that expected from the original combination of one-third of 145, or 48 kg. Thus is illustrated one of the common methods for determining synergism, i.e., measuring the effect of the separate components at given concentrations, then comparing the expected additive elfect with that actually obtained by combinations containing decreased quantities of the separate components.

From the values shown in the third and last lines of Table IV it is obvious that due to the synergistic effect the high increase in weld load due to the antimony phos phorodithioate above can be maintained by substituting a large part of it with the much less expensive lead naphthenate. (A decrease from 3.0% to 1.0% phosphorodithioate.)

EXAMPLE 5 4-Ball Weld Load Test using antimony di(nonylphenyl) phosphorodithioate and sulfurized sperm oil in a mineral oil base grease TABLE V Lithium grease containing- Sb di(nn- 4-ball weld load, kg. ylphenyD- Sulfurized phosphoro- Increase sperm oil, dithioate, percent percent Observed Observed Calculated Thus it is shown that far more than additive efi'ect was obtained when the two E.P. agents, sulfurized sperm oil and antimony di(nonylphenyl)phosphorodithioate were present in combination in a lithium grease. This cooperation between the two E.P. agents was unexpected, and it amounted to almost double the calculated increase in weld load (90 kg. as opposed to 50 kg).

EXAMPLE 6 Timken Load-Bearing Test using antimony di-n-propylphosphorodithioate and lead naphthenate in a grease To separate portions of an aluminum complex mineral oil base lubricating grease were added: 1.5% by weight of lead naphthenate; 0.75% of antimony di-n-propylphosphorodithioate; 1.0% of antimony di-n-propylphosphorodithioate; a combination of 1.5% lead naphthenate and 0.75% antimony di-n-propylphosphorodithioate; and a combination of 1.0% lead naphthenate and 0.5% antimony di-n-propylphosphorodithioate. An untreated portion of the aluminum complex grease served as control. The compositions thus prepared were subjected to the Timken O.K. Load Test described in Example 1 modified by pumping the test grease against the ring and block at the rate of about 1.5 ounces of grease per minute. The results of these tests are tabulated below:

TABLE VI Aluminum Complex Grease Containing Timken O.K. load, lbs. Sb di-n-pro- Lead naphtha pylphqs- Increase nate percent phorodithioate percent Observed Observed Calculated 6 EXAMPLE 7 4-Ball Weld Load Test using antimony bis(2-ethylhexyl) phosphorodithioate and lead diamyl dithiocarbamate TABLE VII SAE base oil containing Sb bis(2- ethylhexyD- Lead diamyldiphosphorodithiocarbamate, thioate, percent percent 4-ball E.P. weld load, kg.

Increase Observed Calculated Observed These data show that the observed increase for the combination of 2.0% lead diamyldithiocarbamate and 3.0% of the antimony phosphorodithioate was significantly in excess of the calculated increase (270 kg. over 230 kg).

We claim:

1. Lubricating compositions exhibiting synergistic extreme pressure and antiwear properties consisting essentially of (1) antimony dihydrocarbylphosphorodithioates, wherein the hydrocarbyl group is selected from the group consisting of (A) alkyl radicals containing from two to eight carbon atoms, and (B) substituted and unsubstituted phenyl radicals with the substituted radicals containing at least one substituent selected from the group consisting of alkyl radicals containing from one to nine carbon atoms; (2) one or more extreme pressure agents selected from the group consisting of lead naphthenate, halogenated parafiin, sulfurized fatty oils and metal dialkyldithiocarbamates, wherein the alkyl groups have a chain length of from one to twenty carbon atoms; and (3) a lubricating base selected from the group consisting of lubricating oil and lubricating grease bases.

2. A lubricating composition as described in claim 1, wherein the phosphorodithioate is antimony di-n-propylphosphorodithioate, and the second extreme pressure agent is chlorinated paraflin.

3. A lubricating composition as described in claim 1, wherein the phosphorodithioate is antimony bis(2-ethylhexyl)phosphorodithioate and the second extreme pressure agent is chlorinated parafiin.

4. A lubricating composition as described in claim 1, wherein the phosphorodithioate is antimony di-n-propylphosphorodithioate and the second extreme pressure agent is lead naphthenate.

5. A lubricating composition as described in claim 1, wherein the phosphorodithioate is antimony bis(2-ethylhexyl)phosphorodithioate and the second extreme pressure agent is lead naphthenate.

6. A lubricating composition as described in claim 1, wherein the phosphorodithioate is antimony di(nonylphenyl)phosphorodithioate and the second extreme pressure agent is sulfurized sperm oil.

7. A lubricating composition as described in claim 1, wherein the phosphorodithioate is antimony di-n-propylphosphorodithioate and the second extreme pressure agent is lead naphthenate.

8. A lubricating composition as described in claim 1, wherein the phosphorodithioate is antimony bis(2-ethyl- 8 hexy1)phosphorodithioate and the second extreme pres- 2,976,122 3/ 1961 Ertelt. sure agent is lead diamyldithiocarbamate. 3,222,280 12/1965 Wolfram et a1.

3,269,946 8/1966 Wiese. References Cited UNITED STATES PATENTS 5 PATRICK P. GARVIN, Primary Examiner 2,511,630 6/ 1950 Goren et a1. W. J. SHINE, Assistant Examiner 2,773,860 12/1956 Musselman.